The present invention generally relates to wireless receivers, and more particularly to estimating a signal quality metric, i.e., a signal-to-interference ratio (SIR), in a wireless receiver.
Receivers in wireless networks typically estimate one or more signal quality metrics to process the received data, to evaluate channel conditions, and/or to generate control signals related to current channel conditions. One signal quality metric of particular interest to wireless receivers is the signal-to-interference ratio (SIR) associated with the received signals. Conventional receivers typically calculate the SIR of received signals and use the calculated SIR, for example, to generate a power control command or a channel quality indication (CQI). For example, a mobile station may transmit a power control command determined based on an estimated SIR to the base station to control the transmit power of the base station on a downlink communication channel. Similarly, a mobile station may provide the base station with a channel quality indication (CQI) based on the estimated SIR. The base station may use the CQI for link adaptation and rate control.
The accuracy of the channel feedback depends on the accuracy of the SIR estimates. In turn, the accuracy of the SIR estimates depends on the amount of time available to perform the calculation, the complexity of the receiver architecture, and/or existing architecture constraints.